1. Field of the Invention
The present invention relates to a high-efficiency all-digital transmitter.
2. Description of Related Art
High-efficiency transmitters are preferred in wireless communications because they allow longer talk time and/or longer battery life. Conventional high-efficiency transmitter may use, for example, polar modulation schemes. However, polar domain signal processing and supply modulation in the polar modulation scheme use two separate paths to a power amplifier, an amplitude modulation (“AM”) path and a phase modulation (“PM”) path. The AM path and the PM path have delay mismatch problems to the power amplifier, which can make it difficult to build a supply modulator required for the AM path. Thus, it is difficult to implement a supply modulator, which has high bandwidth, low noise, and high efficiency. Therefore, production of the conventional high efficiency transmitters is costly.
Thus, there is a need for a low cost high-efficiency all-digital transmitter.